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Microsoft Silverlight is a cross-browser, multi-environment plug-in that delivers the next generation of Microsoft .NET–based media experiences and rich interactive applications for the web. This article describes Silverlight 4 general distribution release version 4.0.60129.0. This update was released on February 14, 2011.

An update is available for Microsoft Silverlight. This update offers a new build (version 4.0.60129.0) that is an upgrade to earlier versions of Silverlight. This update is included in current Silverlight installers. If your computer does not have Silverlight installed, the installer will be offered to you by Microsoft Update or by Windows Server Update Services (WSUS). The WSUS Feature Pack will be available soon.

Installation information

Silverlight site

The Silverlight installer includes all earlier updates in addition to this update. To install the latest version of Silverlight on your computer, visit the following Microsoft website:

Get Microsoft Silverlight

Microsoft update

This update is also available to users of Microsoft Update. If you have an earlier version of Silverlight installed on your computer, this update will be offered as "Update for Microsoft Silverlight (KB 2495644)."

Issues that are fixed by this update

Issue 1

When you play content for Silverlight by using the VC-1 codec, the time stamp is changed to an incorrect value. This issue occurs when the time stamp of the content is greater than 2 to the power of 4.8 nanoseconds. When this issue occurs, you may experience the following symptoms:

When you play the content, the video does not play correctly. However, the audio does play correctly.

When you play the content in the Windows Internet Explorer, an “Errors on Page” message is displayed on the lower-left corner of the window. If you double-click this message, a System.OverflowException exception is thrown and the following following call stack is generated:

Issue 2

The Microsoft Visual Studio IDE crashes when you open a Silverlight application that has a Pixel Shader effect in a performance profiler.

Issue 3

Silverlight 4 does not run on 64-bit versions of Mozilla Firefox for Mac OS X. This update changes plug-in hosting behavious. This update enables Silverlight to run as a 32-bit process in 64-bit versions of Firefox for Mac OS X.

Issue 4

A "6207" DRM error occurs after you upgrade Silverlight.

Issue 5

A memory leak occurs if a Silverlight 4 application has an inline data template in a control.For more information about this issue, visit the following Microsoft website:

Feature that is added by this update

This update adds a feature that improves Silverlight network latency by up to 90 percent. The feature is designed for Silverlight applications that are built by using Silverlight version 4.0.60129.0 or later versions. For more information about how to use this feature in your applications, click the following article number to view the article in the Microsoft Knowledge Base:

2505882
(http://support.microsoft.com/kb/2505882/
)
How to benefit from improved HTTP stack latency in Silverlight 4 version 4.0.60129.0

The third-party products that this article discusses are manufactured by companies that are independent of Microsoft. Microsoft makes no warranty, implied or otherwise, about the performance or reliability of these products.